Retainer-stripper unit for punch presses



y 1949' Y J. H. PARSONS 2,468,998

RETAINER-STRIPPER UNIT FOR PUNCH PRESSES Filed Jan. 21, 1947 Patented May 3, 949

RETAINER-STBIPPER UNIT FOR PUNCH PBESSES John H. Parsons, Pontiac, Mich.

Application January 21, 1947, Serial No. 723,422

8 Claims.

This invention relates to punches, die-presses and the like, and more particularly to a combined stripper and retainer unit adapted for convenient mounting with a punch or like tool upon stamping and similar presses.

While individually removable punches are well known in the trade, and have been used in multiple in a single press, it has long been the custom to use stripping mechanism therewith in the nature of a large stripper plate for all the punches, which is held in place by threaded retaining studs maintaining under compression a number of springs interposed between the stripper plate and punch-holding element. Springs crystallize with use and to replace a defective spring it has been necessary to tear down the assembly, usually in the tool room after removal from the punch press, with consequent loss of time and undue expense. One of the objects of the present invention is the arrangement of stripper mechanisms in punch and similar presses wherein defective springs may be quickly and individually removed at the punch press and as quickly replaced by another, reducing the idletime of the punch press during such replacement to less than a minute.

Another object of this invention is the provision of punch and stripper units in punch presses and the like, wherein the stripper portion thereof may be removed at will without disturbing the position of the associated punch portion, and various punches may be substituted at will for use with the same stripper portion of the unit.

A further object of this invention is the novel mounting of a quickly demountable stripper unit for an individual punch or like tool upon the same press element as the punch and with stripper means surrounding the punch, but without being secured to or in any way carried by the punch.

A further object of this invention is the provision of a spring-pressed clamp for securing the stripper means upon the retainer block in operative position adjacent the punch, the clamp having an elongated head engaging a comparatively large portion of the stripper plate when turned in one direction, and adapted to pass quickly through an elongated slot in the stripper plate when turned in another direction, whereby rapid mounting of the stripper-means upon the retainer block and rapid removal therefrom is achieved.

, Other objects and advantages will be apparent from the following description wherein reference is made to the accompanying drawings illustrating a presently preferred embodiment of the in vention, and wherein similar reference numerals designate similar parts throughout the several views.

In the drawings:

Fig.- 1 is a plan view of my improved punch retainer and stripper unit.

Fig. 2 is a vertical longitudinal section therethrough, taken substantially on line 2-2 of Fig. 1.

Fig. 3 is an end elevation, looking from the right in Fig. 1, and with the stripper spring compressed as during a punching operation, a, fragmentary vertical section through the work and companion die being illustrated.

Fig. 4 is a vertical cross section taken substantially on line 4-4 of Fig. 2, with the fragmentary portion of the work and companion die of Fig.3 shown in elevation.

Fig. 5 is a side elevation of the stripping unit detached from the retainer block, parts being broken away, and

Fig. 6 is a bottom plan view of the detached stripping unit.

Referring now to the drawings, reference numeral l0 designates the retainer block adapted to be regidly secured to a press member, as the movable head or ram, by screws or the like extending through bores I I in the retainer block, and a cover plate I2 secured thereon, as by screws I3 (Fig. l). Retainer block I0 is provided with a bore I4 for the reception of the shank I5 of the punch or other tool, and is demountably secured therein in substantially the manner disclosed in Letters Patent No. 2,107,581, issued February 8, 1938, to John H. Parsons and Lawrence S. Lamb. As shown in Fig. 2, the punch shank I5 is provided adjacent its upper end with a transverse groove IS, the upper wall of which is inclined and arranged to be contacted by the curved nose of locking detent I8 mounted for horizontal movement in a recess I9 in the retainer block which opens into the bore I 4. A wedging cam member 20 is mounted for vertical movement in recess I9, and the adjacent walls of detent I8 and wedging member 20 are inclined substantially as shown, so that downward pressure exerted upon wedging member 20 will tend to force detent I8 into firm engagement with the inclined upper wall of slot I6 and so press the punch shank I 5 upwardly against cover plate I2. The angle between the contacting walls of wedge member 20 and locking detent I8 is such that the wedge cannot be forced upwardly by the horizontal component of force engendered by pressure on the punch I 5 when the press is operated. Also the upper surface of the nose of the lock ing detent is arranged so that, when the wedging member 28 is moved away from the detent, the detent readily recedes from the punch 65, permitting the punch to be removed by a downward pull thereon. From the wedging member 2% depends a stem 2! of a diameter to readily pass through the apertured lower wall of recess i9 (Fig. 2), and the lower end of stem M is secured to a cupped collar 22 of larger diameter, and arranged to slide within bore 23 extending from the lower edge of block Hi to within a short distance of the bottom of recess 19, the upper wall of bore 23 serving as a shoulder limiting the upward movement of coil spring 2 1 surrounding the stem 2i between such shoulder and collar 22, substantially as shown. Spring 24 is thus arranged to exert a constant pressure forcing locking detent is into engagement with the punch shank through the wedging cam member 28. An aperture 25 of sulficient area to permit the passage of the wedging member 2!] is provided in backing plate i2, and upward pressure upon collar 22 will serve to move wedging member 26 upwardly into recess 25., and out of engagement with locking detent 58, whenever it is desired to. remove the punch 15 or other tool with which it is associated.

The stripper means adapted to be demountably secured to retainer block iii in position to strip the work perforated by punch i will now be described. A stripper plate 26, herein shown as conforming in size and configuration to retainer block it], but which may be of other shapes, is provided with a cylindrical bore 2i adjacent one extremity for the reception of stripper sleeve 28. As best shown in Figs. 2 and 4, bore 2"! is formed with a large upper portion extending to slightly above the lower surface of plate 25 and a concentrio smaller opening through such lower portion of plate 28, whereby a shoulder is formed limiting the downward movement of sleeve 28 by contact with a flange on the upper portion of such sleeve. Stripper sleeve 28 is provided with a central bore of slightly greater diameter than the punch shank l5 through the major portion of its length, and a concentric bore of lesser diameter at. its lower extremity, such smaller bore being but slightly greater in diameter than the punch point l5a. Accordingly, sleeve 2% acts as a guide for the lower portion of the punch, but may slide relatively thereto after contacting the work during the operation of the press. A strong coil spring 29 surrounds sleeve 28 and is adapted to be put under initial compression between stripper plate 26 and spring retaining collar 36 so that the flange at the upper end of sleeve 28 is maintained in constant engagement with the shoulder at the lower extremity of bore 21 at all times except when the stripper means is in contact with the work. Spring retaining collar 33 is secured in position by means of a split resilient ring 3! fitting in a shallow circular groove 32 in the outer periphery of the lower portion of sleeve 28. C01- lar 30 is provided with a smaller bore through its upper portion and a concentric larger bore through its lower portion, substantially as shown in Figs. 2 and 4, the lower bore being of a diameter slightly less than that of split ring 3! when fully open, so that ring 3! must be compressed slightly to insert it in collar 3%. To assemble collar 35) upon stripper sleeve 28, the flange at the upper end of such sleeve is. held in engagement with the shoulder in plate 26, then coil spring 29 is placed around the projecting portion of sleeve 23, and then collar 3! with split ring 3! therein is pushed along the exposed extremity of sleeve 28 until split ring ti enters the shallow groove 32 in sleeve 28, coil spring 29 being initially compressed during such sliding of collar 30. Preferably suflicient compression is thus imparted to spring 29 so that thereafter sleeve 23 and collar 39 will move simultaneously when brought in contact with the worlr during the press operation.

Stripper plate 25 is demountably secured upon retainer block Hi by means of the spring-controlled clamp now to be described. Retainer block W is provided with cylindrical bore 35 remote from punch shank i5, such bore terminating short of the lower surface of block 10, and a concentric bore of lesser diameter extends through the remaining portion of block I0, whereby a wide shoulder is provided at the lower end of bore 35 for engagement by the lower end of a strong coil spring 36 (Fig. 2). Spring 36 surrounds the stem 3'! of the clamp and its upper end engages the lower surface of clamp head portion 38. As herein shown, stem ill and head 38 of the clamp are integral and the lower extremity of stem 3'? is threaded. A clamp foot 39 is threadedly mounted upon stem 31 and when adjusted to the position that will eiiect the desired compression of, spring 36 when the clamp is holding the stripper means against block I0, foot 39 is pinned to stem 31, as by cross-pin 40. Clamp foot 39 is, herein shown as comprising an internally threaded cylindrical body portion with a solid polygonal lower extremity 39a, formed to receive a wrench whereby the clamp may be partially rotated whenever desired. Some of the fiat surfaces forming the polygonal extremity 39a may be aperturecl for the reception of a spanner wrench or the like, whenever it is desired to lower the clamp into locking position as hereinaiter described. An elongated clamping member d! extends horizontally beyond the periphery of clamp member 39, and is arranged so that the spring pressure of spring 36 will be exerted upon stripper plate 25 over a wide area. Plate 26 is provided with a bore 42, best shown in Figs. 5 and 6, wherein the central portion is cylindrical and of slightly greater diameter than that of the body portion of clamp member 39, and lateral extensions 42a are arranged transversely of plate 25 to form with bore 42 an elongated transverse slot through which clamp member 4| may pass, when such clamp member is turned to align with such slot. This position is assumed when it is desired to release the stripper means from the retainer block. As long, however, as it is desired to maintain the stripper plate 26 in position upon the retainer block, the clamp member 4| is turned in some direction other than that wherein it would pass through bore 42. Preferably clamp member 6! is maintained at right angles to the elongated slot formed by the lateral extensions 42a of bore 42, or in other words, in substantial alignment with the longitudinal axis of plate 26. To facilitate the maintenance of such position a shallow groove 43 may be cut in the lower surface of plate 26 to form a seat for clamp member 4|.

In operation, whenever it is desired to supply stripper means for use with punch [5, plate 26 and attached stripper means may be slid upwardly over the punch shank with its bore 42 aligned with clamp member 4|.

An intermediate cylindrical bore 44 may be arranged in the upper portion of plate 26 to fit over the depending collar 22 or the punch shank retaining means. The. polygonal extremity 39a of the clamp is then grasped by a spanner wrench or the like and pulled downwardly against the tension of spring 35 until clamp member 4| is entirely below stripper plate 26. The clamp is then rotated through substantially a right angle to seat clamp member H in the shallow groove 43. The spring pressure exerted through the elongated clamp member 4| will serve to maintain the stripper mechanism in constant engagement with retainer block ll} until released.

While in position, the stripper means will move vertically with retainer block it during the operation of the punch press. As the ram descends, collar 30 of the stripper means engages the Work 58 ahead of the punch point l5a, serving to firmly hold the work while the punch passes through the work in conjunction with companion die 5| to extrude a slug 52 therethrough, in the usual manner of perforating presses. As the ram ascends, the stripper spring 29 will hold down collar 30 and the work until punch point [5a has moved to a position above the work, and then move upwardly with the ram.

Replacement of one stripper-means unit by another requires only the turning of clamp member 4| through ninety degrees to align it with said elongated slot, whereupon spring 36 pulls clamp member 4| upwardly, freeing stripper plate 26 and its attached stripper mechanism. The stripper-means unit is then slid downwardly below the punch, and another unit substituted therefor.

While the stripper unit is detached from retainer block it], punch l5 may readily be removed for examination or replacement, by merely pushing upwardly upon collar 22 until wedging member 20 is out of contact with detent l8 and then pulling downwardly upon the punch.

Although the specific embodiment of the invention herein disclosed is believed to adequately fulfill the objects and advantages herein stated, it is to be understood that the invention is adaptable to other forms and that various modifications and changes may be made therein without departing from the scope of the invention as indicated in the subjoined claims.

I claim:

1. A retainer-stripper unit for use in presses comprising a retainer block having a plurality of spaced bores therethrough, a punch mounted in one of said bores and extending beyond a face of said block, stripper means for said punch springpressed against said face of the block, said stripper means including a plate adapted to engage said face of the block, resilient work-engaging means carried by said plate in position to engage the work in advance of the punch when the press is operated, and spring-controlled securing means for said plate mounted in another of said bores and passing through an aperture in said plate.

2. A retainer-stripper unit for use in presses comprising a retainer block having a plurality of spaced bores therethrough, a punch mounted in one of said bores, and extending beyond a face of said block, stripper means for said punch engaging said face of the block including a multiapertured plate adapted to engage said face of the block, a sleeve slidably mounted in an aperture in said plate, a spring surrounding said sleeve, a collar secured on said sleeve in position to partially compress said spring between said plate and said collar, and means for resiliently clamping said plate against said block mounted in another of said bores and passing through another of said apertures in the plate.

3. A retainer-stripper unit for use in presses iii comprising a retainer block having a plurality of spaced bores therethrough, a punch mounted in one of said bores, and extending beyond a face of said block, stripper means for said punch engaging said face of the block including a multiapertured plate adapted to engage said face of the block, a sleeve slidably mounted in an aperture in said plate, a spring surrounding said sleeve, a collar secured on said sleeve in position to partially compress said spring between said plate and said collar, and a clamp mounted in another of said bores and passing through another of said apertures in the plate, said clampbeing movable into and out of contact with the face of the plate remote from said block.

4. In punch presses, a retainer block adapted to be secured to a movable press member, a punch demountably carried thereby and extending from a face of the block, stripper means for said punch adapted to engage said face of the block, and means carried by said block for resiliently holding said stripper means against said block, comprising a clamp having an elongated clamp member movable into position to engage said stripper means over an extended area.

5. In punch presses, a retainer block adapted to be secured to a movable press member, a punch demountably carried thereby and extending from a face of the block, stripper means for said punch adapted to engage said face of the block, and means carried by said block for resiliently holding said stripper means against said block, including a turnable clamp having an elongated clamp member extending beyond said face of the block, said stripper means including a plate provided with an elongated slot through which said clamp member is adapted to pass when turned in one direction, and then engage said plate over an extended area when turned in another direction.

6. In punch presses, a retainer block adapted to be secured to a movable press member, a punch demountably carried thereby and extending from a face of the block, stripper means for said punch including a plate adapted to engage said face of the block and provided with an elongated slot therethrough, and means carried by said block for resiliently clampin said stripper means against said face of the block, including a turnable clamp member having an elongated clamp portion arranged to pass through said slot when aligned therewith.

7. In punch presses, a retainer block adapted to be secured to a movable press member, a punch demountably carried thereby and extending from a face of the block, stripper means for said punch including a plate adapted to engage said face of the block and provided with an elongated slot therethrough, and means carried by said block for resiliently clamping said stripper means against said face of the block, including a turnable clamp member having an elongated clamp portion arranged to pass through said slot when aligned therewith, said clamp member also having a polygonal portion remote from said block for engagement by a wrench to facilitate turning of said clamp member.

8. A retainer-stripper unit for use in presses comprising a retainer block having a plurality of spaced bores therethrough, a punch mounted in one of said bores and extending beyond a face of said block, stripper means for said punch engaging said face of the block including a multi-apertured plate adapted to engage said face of the block, a sleeve slidably mounted in an aperture shouldered central bore, and a split ring arranged in said groove and bearing against the shoulder of said collar bore to demountably secure said collar upon said sleeve with said spring under compression.

JOHN H. PARSGNS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 654,197 Clark Apr. 30, 1867 370,100 Stimpson Sept. 20, 1887 473,889 Schaake Apr. 26, 1892 524,691 McLane Aug. 14, 1894 2,350,436 Whistler June 6, 1944 

